Many attempts have been made to simulate natural daylight by artificial means. Some of the more successful devices for this purpose are described in U.S. Pat. Nos. 5,079,683; 5,083,252; and 5,282,115. The entire disclosure of each of these U.S. patents is hereby incorporated by reference into this specification.
The apparatus of U.S. Pat. No. 5,282,115 is illustrative of these prior an devices. This apparatus contains a light source and a single filter. The single filter is comprised of a color correcting filter material and a neutral density filter material. As the apparatus is being adjusted, the spectral distribution of the light which passes through it varies continuously, but the brightness and/or illuminance of such light is substantially constant.
However, none of the devices of the above U.S. patents, and none of the prior art devices known to applicant, readily lend themselves for use in many commercial and residential settings. Thus, e.g., such prior art devices cannot readily be used in the dressing rooms of clothes stores, in jewelry stores, on the counters of cosmetic departments of department stores, in design studios, and the like.
U.S. Pat. No. 3,794,828 of Arpino discloses an appliance containing a plurality of incandescent lamps and makeup mirrors disposed in a portable case; some of the lamps are unfiltered, and some are provided with red filters. The lamps are so configured that the amount of power delivered to different lamps in the system may be varied, thereby varying the spectral outputs of such lamps.
In order for the appliance of the Arpino patent to function, it must utilize lamps with wattage ratings such that the wattage rating of one lamp is at least three times the wattage rating of another lamp. In many applications, where relatively high wattages are required, this three-to-one ratio is not feasible.
It is an object of this invention to provide an apparatus for controlling the illumination of two or more light sources, each with a different color temperature characteristic, so that the resultant color temperature produced is a blend of the color temperature of the individual sources and the desired color temperature and illumination will be reliably produced by the apparatus.
It is another object of this invention to provide an apparatus for controlling the illumination of two or more light sources, each with a different color temperature characteristic, so that the resultant color temperature produced is a blend of the color temperature of the individual sources and a range of desired spectral outputs and color temperatures can be produced with the device.
It is another object of this invention to provide an apparatus for controlling the illumination of two or more light sources, each with a different color temperature characteristic, so that the resultant color temperature produced is a blend of the color temperatures of the individual sources, and which apparatus can vary either the overall color temperature or the illuminance of the blend while holding the other relatively constant.
It is an object of this invention to provide an apparatus for controlling the illumination of two or more light sources, each with a different color temperature characteristic, so that the resultant color temperature produced is a blend of the color temperature of the individual sources, which apparatus is an electronic control unit and may be relatively inexpensive, lightweight and/or small in size.
It is an object of this invention to provide an apparatus for controlling the illumination of two or more light sources, each with a different color temperature characteristic, so that the resultant color temperature produced is a blend of the color temperature of the individual sources, which apparatus is especially suitable for use with a lamp with a coated reflector and light source which produces a spectral output which is substantially identical to daylight.
It is another object of this invention to provide an apparatus for controlling the illumination of two or more light sources, each with a different color temperature characteristic, so that the resultant color temperature produced is a blend of the color temperature of the individual sources, wherein said apparatus is comprised of a feedback system which monitors and stores in memory the spectral output and/or the illuminance of the device and makes necessary corrections to the power supplied to the light sources.
It is another object of this invention to provide an apparatus for controlling the illumination of two or more light sources, each with a different color temperature characteristic, so that the resultant color temperature produced is a blend of the color temperature of the individual sources, wherein said apparatus can be combined with prior art light booths to improve their reliability and output.
It is another object of this invention to provide an apparatus for controlling the illumination of two or more light sources which can store the illumination characteristics of the light sources and can be calibrated to operate the light sources at predetermined illumination and color temperature ranges.
It is another object of this invention to provide an apparatus for controlling the illumination of two or more light sources which do not necessarily need exact wattage ratios and by delaying the conductance and applied voltages to the light sources.
It is yet another object of this invention to provide an apparatus for controlling the illumination of two or more light sources which readily can be used in the dressing rooms of clothes stores, in jewelry stores, on the counters of cosmetic departments of department stores, in design studios, and the like.